Particularly in the larger cities where theft and pilferage are widespread, delivery trucks are a prime target of thieves as such trucks frequently are unoccupied for periods of time while the drivers are away from their trucks delivering or picking up packages. In an effort to combat such theft, most delivery firms now use a truck with security arrangements consisting of (i) an enclosed storage area having a rear loading door which normally is kept locked after the truck has been loaded for the day's deliveries and (ii) a bulkhead positioned internally of the vehicle between the cab and storage areas and provided with a sliding door which is to be kept locked any time the driver is not in the truck.
In theory, such security arrangements should provide adequate protection. As a practical matter, however, they often fail because of the time and effort required of a driver to manually unlock, open, close and relock the interior sliding door every time a delivery or pickup is made. Depending upon the number of deliveries and/or pickups made, the average driver can lose one half to one hour per day in locking, unlocking, opening and closing the interior security door. Wishing to avoid this loss of time and complete their rounds as quickly as possible, many drivers tend to leave the interior security door unlocked and even open while out of their trucks making a delivery or pickup. As a result, considerable theft still occurs.
Over the years, various suggestions have been proposed for locks and locking systems intended to improve the security of delivery trucks and other types of vehicles and mobile units. Aside from the system disclosed in U.S. Pat. No. 4,866,963, however, none of these prior suggestions have met with any significant success in providing an effective, safe, inexpensive and simple security system capable of meeting the needs of today's transportation and delivery industry.